🛡️ Error Handling

Error handling is crucial for building robust Python applications. Python provides powerful tools to catch, handle, and recover from errors gracefully, preventing crashes and providing meaningful feedback to users.

# Basic error handling
try:
    result = 10 / 0
except ZeroDivisionError:
    print("Cannot divide by zero!")
    result = 0

print(f"Result: {result}")

# Multiple exception types
try:
    number = int("abc")
except ValueError:
    print("Invalid number format")
except Exception as e:
    print(f"Unexpected error: {e}")

🎯 Why Error Handling Matters

Proper error handling helps you:

Prevent Crashes 💥: Keep applications running
User Experience 😊: Provide helpful error messages
Debugging 🔍: Identify and fix issues quickly
Data Safety 🔒: Protect against corruption
Maintenance 🔧: Build reliable, maintainable code

📚 Error Handling Topics

Master Python's error handling capabilities:

🚨 Handle Exceptions Learn try/except blocks and exception handling patterns.
⚡ Create Custom Exceptions Build your own exception classes for specific error cases.
🔍 Debug Code Use debugging tools and techniques to find and fix issues.
📝 Use Logging Implement logging for tracking errors and application behavior.
🔄 Implement Retry Logic Add resilience with automatic retry mechanisms.

📊 Exception Reference Tables

Common Built-in Exceptions

Exception	When It Occurs	Example
`ValueError`	Invalid value for operation	`int("abc")`
`TypeError`	Wrong data type	`"text" + 5`
`KeyError`	Dictionary key not found	`dict["missing_key"]`
`IndexError`	List index out of range	`list[100]`
`FileNotFoundError`	File doesn't exist	`open("missing.txt")`
`ZeroDivisionError`	Division by zero	`10 / 0`
`AttributeError`	Object has no attribute	`"text".missing_method()`
`ImportError`	Module import fails	`import nonexistent`

Exception Handling Patterns

Pattern	Use Case	Example
Basic try/except	Handle single exception	`except ValueError:`
Multiple except	Handle different errors	`except (ValueError, TypeError):`
Catch all	Handle any exception	`except Exception:`
Exception info	Get error details	`except Exception as e:`
Finally block	Always execute cleanup	`finally:`
Else block	Run if no exceptions	`else:`

🌟 Quick Examples

Here's what you'll learn to handle:

# File handling with errors
try:
    with open("data.txt", "r") as file:
        content = file.read()
        print("File read successfully")
except FileNotFoundError:
    print("File not found")
except PermissionError:
    print("No permission to read file")

# Data conversion with errors
try:
    user_input = "25"
    age = int(user_input)
    print(f"Age: {age}")
except ValueError:
    print("Please enter a valid number")

# Custom error handling
class CustomError(Exception):
    pass

try:
    raise CustomError("Something went wrong")
except CustomError as e:
    print(f"Custom error: {e}")

🏗️ Error Handling Hierarchy

Understanding Python's exception hierarchy helps you catch errors effectively:

BaseException
 +-- Exception
      +-- ValueError
      +-- TypeError  
      +-- KeyError
      +-- IndexError
      +-- FileNotFoundError
      +-- ZeroDivisionError
      +-- AttributeError
      +-- ImportError

Build robust Python applications that handle errors gracefully! 🛡️✨

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